Yes, it is possible to configure the POS system in Odoo 15 to only show one contact and address per customer when searching for customers. Here are the general steps you can follow to set this up:

1. Go to the POS app and click on "Configuration" and then "Point of Sale"
2. Under "Contacts" you can choose which contacts you want to show in the POS.
3. You can choose to show only one contact per customer, and you can select which contact you want to show.
4. For addresses, you can set a default address for each customer, and the POS will show only that address.
5. You can also customize the POS views, and remove the fields that you don't need to see.

Please note that the above steps are general, and the process may vary depending on the version of Odoo you are using and your specific setup. You may need to consult the documentation for further information on how to set up the POS in Odoo.

Alternatively, you can consider creating a new contact for each customer that will be used for the POS, this way you can have a specific contact for the POS and keep the other contacts for other uses.